Didn’t know this was a thing: my muffler exploded while cruising down the freeway. Scared the bejeezus out of out of me. I’m just tooling along about 65 mph on a sunny day in light traffic, when I felt a funny vibration, a loss of power, then ka-boom. A really, really loud ka-boom, an Iraq kind of loud. And then silence as I coasted to the side of the freeway. I have yet to diagnose the cause, but I’m 99 percent certain it’s an ignition problem. I feel blessed the seam of the muffler was oriented away from the fuel tank. (Specs: ’73 Maverick 4-door, 302, C4, bone stock except Pertronix Ignitor)
Probably right about ignition problem, we used to make cars do it all the time years ago by turning the key off and back on and sometimes the results ended looking just like your muffler. Thanks for bringing back a past memory
you've got a fuel problem, it's running rich enough to dump fuel into the exhaust where it collects in the muffler. When the conditions and the fuel/air mix has permeated the exhaust, the all that's needed is a flame from an open exhaust valve to set it off.
It can happen both ways, either carb float sticking and dumping excess fuel till the point of exhaust system saturation and ignition.. or intermittent spark issues causing the same exhaust fuel saturation effect. IME, it's usually ignition related and anyone who's hotrodded bunch's of old points style ignitions has probably had this happen at least one time or another through the years. Also had it happen after smacking exhaust valves into pistons at least twice that I can recollect. And if you run welded mufflers and you're at the end of a high speed/full throttle run.. it can literally tear or blow header gasket bits and even toss mufflers off their slip fit connections. Boooommm!.. followed by scraping metal sounds as you try to not over-react from the flood of adrenalin. This thread is making me nostalgic! PS.. just noticed that too small tail pipe inserted into the rear of that muffler. Horrible idea for any sort of free flowing exhaust system. Get a proper reducer and fix it while the muffler is off.
.. something in there needed to get out... (if photobucks allows similar problem while tuning timing and AFR (turbo 250): have fun
